Vitamin B6
Vitamin B6 (pyridoxine) has, Dr. Dörr explains, multiple metabolic functions, especially in the metabolization of amino acids, and is important from a neurologic perspective. For girls, the vitamin is important for hormone metabolism. Data show that approximately 14% of girls aged 14-18 years ingest less than the recommended amount of vitamin B6. For vegans, the percentage of those with insufficient intake is even higher, since vitamin B6 has low bioavailability in plant-based foods. For girls, there is the additional factor of oral contraceptives. There are indications that those who use oral contraceptives containing estrogen have lower levels of pyridoxal-5’-phosphate (PLP), a marker for vitamin B6. Since the PLP-dependent enzymes are essential for the synthesis of hormones such as serotonin, symptoms such as depressive moods, increased irritability, nervousness, and loss of libido can indicate a vitamin B6 deficiency.
The daily B6 requirement for girls is 1.4 mg and can be fulfilled, for example, by consuming 200 g of hazelnuts, 200 g of walnuts, 400 g of bananas (two to three bananas, depending on weight), 700 g of cooked green beans, 1 kg of cooked potatoes, and 1.4 kg of oats.
Vitamin B12
Since vitamin B12 is not present in plant-based food, following a vegan diet in the long term can result in deficiency unless dietary supplements are taken. When researching the choices of various dietary supplements, it should be taken into consideration that the utilization of vitamin B12 from plant-based sources such as algae, seaweed, and fungi is not necessarily a given. Careful selection and regular monitoring of B12 status is recommended.
Vitamin D
According to Dr. Dörr, evidence has increased in recent years that vitamin D is crucial not only for the bones but also for numerous metabolic processes. The fact is that foods are barely capable of covering the vitamin D requirement in amounts that can be expected to be consumed. Vegan foods are not able to contribute to the supply of vitamin D, since considerable amounts are present only in food of an animal origin. The decision to take supplements and in what amounts should be made on the basis of one’s condition.
Minerals
Calcium, iodine, iron, selenium, and zinc are not easily available in sufficient quantities from a purely plant-based diet. Plant-based foods usually contain lower quantities of these minerals than do foods of animal origin, and the minerals from plant-based sources have lower bioavailability. According to Dr. Dörr, current evidence suggests that a vegan diet can have negative effects on bone health. In an ongoing cross-sectional study, ultrasound measurements of the heel bone are being made, and biomarkers in the blood and urine are being measured. On average, people who follow a vegan diet have lower ultrasound readings than those of omnivores.
The European Prospective Investigation into Cancer and Nutrition (EPIC) study from Great Britain, which involved almost 55,000 people, revealed that vegans had a 43% higher risk of fracture, compared to meat eaters.
An important nutrient, especially for cell development, is choline, which, Dr. Dörr explains, can be absorbed mainly through eating eggs, fish, meat, and dairy products. There is increasing evidence that a vegan diet is not able to supply sufficient quantities of choline, particularly if requirements increase, such as during pregnancy and breastfeeding. Evidence has grown that women who wish to conceive a child benefit not only from a sufficient intake of folate intake for the prevention of neural tube defects and for favorable fetal development but also from sufficient quantities of choline (the recommended daily amount for pregnant women is 480 mg).
A version of this article first appeared on Medscape.com.